Southeastern Australia is currently experiencing a heatwave, leading to elevated bushfire risk, particularly in Victoria and South Australia. While high fuel loads are present, mitigating factors such as deep soil moisture and coastal breezes are influencing fire danger ratings. Concurrently, experts are analyzing the increasing frequency of pyrocumulonimbus cloud formations, a phenomenon associated with intense bushfires, and discussing broader shifts in fire regimes and global climate trends.
Current Conditions and Bushfire Risk
Southeastern Australia is undergoing a weeklong heatwave, contributing to bushfire ignition. Active fires have been reported in Victoria and South Australia, with further outbreaks anticipated. Despite high fuel loads resulting from previous years of rainfall, fire danger ratings are not reaching extreme levels across all areas. This is attributed to the absence of key factors typically associated with catastrophic bushfire conditions, specifically prolonged drought and hot, dry westerly winds.
Current forecasts indicate that winds are predominantly originating from the sea, introducing moist air. Widespread soil moisture levels, which are at least average, allow trees to access water through their root systems, thereby releasing moisture into the atmosphere. This increased moisture content in vegetation and leaf litter necessitates more energy for combustion, potentially leading to less intense fires and aiding firefighting efforts, even in high temperatures. Northern and central Victoria are projected to experience the highest fire danger forecasts within southeastern Australia, primarily due to localized rainfall deficits.
Localized fire incidents have occurred, including 19 homes lost at Dolphin Sands, Tasmania, and 16 homes destroyed at Koolewong, New South Wales. However, former Fire and Rescue NSW commissioner Greg Mullins stated that widespread and dangerous fires comparable to past catastrophic events are considered improbable without a prolonged drought period.
Understanding Pyrocumulonimbus Clouds
A fire in north-east Victoria near Walwa generated a pyrocumulonimbus (pyroCb) cloud on Thursday afternoon, observed at Mt Lawson. These clouds are fire-generated thunderstorms associated with extreme bushfire conditions. They form when intense heat from a fire causes air within the smoke plume to rise rapidly. As this turbulent air ascends and draws in cooler ambient air, moisture within the plume condenses at sufficient altitude, forming a cloud that can produce lightning in an unstable atmospheric environment.
Rick McRae, a bushfire scientist at the University of New South Wales, indicates that pyroCb clouds typically form in very dry landscapes with high potential for combustion, citing critically low river flow in the Albury area as an example of such conditions.
The impacts of pyroCb clouds include:
- Erratic Winds: They generate intense updrafts, altering localized wind patterns and complicating fire direction prediction. These winds can intensify fire behavior and accelerate spread, potentially leading to numerous spot fires.
- Lightning Strikes: Lightning produced by pyroCb clouds can ignite new spot fires at distances of 40-100 kilometers from the primary fire front.
- Lack of Rain: Despite producing lightning, pyroCb clouds generally do not produce rainfall due to a high concentration of dust particles that prevent water droplets from coalescing.
PyroCb events have, in exceptional circumstances, been associated with fire tornadoes and black hail, as seen during the 2003 Canberra bushfires. Professor McRae notes that individual pyroCb clouds typically last for approximately three hours, though multiple events can occur within a single fire incident. The occurrence of pyroCb clouds is increasing, with the first documented instance in Australia in 1983. Prior to 2000, seven events were registered, while over 100 have been registered since 2000, with occurrences doubling during the "Black Summer" bushfire season. This increase is attributed to the accelerating effects of climate change.
Shifting Fire Regimes and Climate Change
Predicting the timing and location of large fire events is becoming more complex due to intricate interactions between climate, fuel, and fire across spatial and temporal scales. Instances of unusual fire behavior, such as winter fires in Los Angeles, have been linked to "hydroclimatic rebound events"—rapid transitions between extreme wet and dry conditions. Australia has experienced similar variability, including a severe drought (2017-2019) followed by a "triple-dip" La Niña (record rainfall and flooding in 2022), with parts of eastern Australia rapidly returning to drought conditions in the subsequent year.
This rapid transition has been observed near Tenterfield in north-east New South Wales, where high-severity fires occurred just four years after similar events during the 2019-20 megafires. This short interval is uncommon for dry sclerophyll forest types, which historically exhibit a minimum of 10 years and an average of 30 years between such events.
While climate change is a contributing factor to shifting fire regimes across Australia, other elements also play a role. These include changes in land management practices, disruptions to traditional cultural burning by Indigenous populations, weed invasion, fire suppression strategies, and the expansion of human settlements into bushland areas.
Global Climate Context and Long-Term Outlook
Globally, 2025 ranked as the third hottest year on record, following 2024 and 2023. Over the past three years, the running average for global temperatures has exceeded 1.5 degrees Celsius of warming since pre-industrial times. Climate scientists from the Copernicus Climate Change Service project that, at the current rate of warming, the 1.5C limit set by the Paris Agreement could be reached by 2030, a decade earlier than initially predicted. This warming trend is primarily attributed to the build-up of greenhouse gases from fossil fuels and exceptionally warm sea surface temperatures, amplified by El Niño events in 2023 and 2024, and remaining high in 2025 without an El Niño.
In 2025, half of the world experienced a higher-than-average number of days of strong heat stress (a 'feels-like' temperature of 32C or above), with Australia facing more extreme heat stress days than average, reaching over 46C in some areas. The World Health Organization identifies heat stress as a leading cause of global weather-related deaths. While individual extreme weather events cannot be solely attributed to climate change, the background climate is understood to increase their probability and risk of occurrence. Forecasts suggest 2026 is also likely to be among the top five warmest years on record globally.
The current La Niña weather cycle, associated with increased rainfall, is projected to conclude soon. Climate change is noted as a factor in the increasing frequency and intensity of droughts in Australia, and a drought developing this year could lead to elevated bushfire risks in the subsequent summer season.
Preparedness and Research Initiatives
As the nature of bushfires evolves and prediction becomes more challenging, there is an increased emphasis on integrating fire research findings into practical management approaches. Following the 2019-20 megafires, the New South Wales government initiated a program to foster collaboration among academics, government agencies, and Indigenous knowledge holders. The NSW Bushfire and Natural Hazards Research Centre integrates end-users into research projects from inception to completion, aiming to generate relevant and applicable fire management strategies.
Authorities advise individuals in affected areas to monitor communications from local fire agencies and adhere to instructions provided by fire services. Mobile applications offering alerts for bushfires and other natural hazards are available in most Australian states.